1) Field of the Invention
The present invention is directed to water reactive materials.
2) Description of Prior Art
The use of reactive powders and in particular powders that react with water are known. This includes the use of such water reactive powders in underwater applications. For example, torpedo warheads utilize powdered forms of low atomic metals, for example, lithium, in order to produce the desired underwater explosion.
Reactions that occur underwater or utilize water as an oxidizing agent, however, are often slowed by the presence of excess amounts water, which cool the desired explosive reaction. Slowing of the reaction decreases the effectiveness of the reaction. Another limitation on the effectiveness of these water reactions results from the premature oxidation of the reactive particles within the reactive material. The size of the particles in the water reactive material also affects the efficiency of the reaction. Using large particles of a water reactive material is inefficient. Smaller particles contact the water with a greater surface area and thereby accelerate the reaction. Reaction time is also limited by diffusion rate. For example, a thick layer of a water reactive material inhibits the reaction by causing a slow diffusion rate.
In general, enhanced shock performance of explosions using water reactive materials comes from increasing the early time frame rate of bubble expansion and sustaining this rate as long as possible. The chemical energy of an underwater explosive is distributed into shock and bubble performance as well as waste energy. Each of the constituents in an underwater explosive contributes to the observed performance. A shock wave initiates the Helium decomposition causing a release of gases and energy, which initiates the chemical decomposition of the oxidizer into gas that drives the early bubble expansion. By increasing the energy release from intimate fuel-oxidizer combinations, i.e., water (oxidizer) and a water reactive material (fuel), in this time frame, an increase in the rate of oxidizer decomposition and, therefore, the shock bubble performance is realized.
Subsequently, the energy released from the fuel reacting with the product gases is generally slow and contributes to the bubble performance. If the expanding mixture is heavy in solids, the conversion of the chemical energy to potential energy will be inefficient and lead to waste energy in the form of hot gases at the end of the bubble expansion. If the expanding mixture is mostly gases, then the peak pressure will be high, but shock wave will only be supported for a short time. Furthermore, the energy from gas producing reactions is generally less than from fuel-oxidizer reactions. However, the conversion of chemical energy to potential energy of the bubble is generally very efficient, leaving no waste energy in the form of hot gases at the end of the bubble expansion. Therefore, a system is needed that optimizes the particle composition and ignition of the water reactive material and improve the mixing of the water reactive material with water in order to improve the resulting explosion.